Note that you may have incurred late tax payment penalties or consequences depending on the situation. IRS Letter 4464C means that the IRS is reviewing your tax return. If you are due a refund, the agency is holding your refund pending review of your tax return. This letter 4800c letter does not mean that the IRS is auditing your return. This is the notice that the IRS sends prior to terminating your installment agreement with the IRS. You must contact…